Polymer brush bilayer under non-equilibrium shear inversion: An MD simulation approach

The polymer brush bilayer under non-equilibrium shear inversion is studied by means of MD simulations with Langevin and DPD thermostats. The temporal evolution of the shear stress reveals that there is an overshoot during shear inversion only with hydrodynamic interactions and the electrostatic interactions completely suppress this overshoot. The overshoot in the shear stress takes place moments after the chains stretch strongly in the opposite shear direction and before the new stationary shear is established. Therefore, nature uses the electrostatic interactions between monomers i.e. Polyelectrolyte brushes to suppress mechanical instabilities in mammalian knee joints which is a very surprising outcome. The results of this study could shed light to our understanding from complex behavior of soft matter systems.